I second Matze's complaint. I am a new returnee to Nisus. I sadly left Nisus Classic for Word. I now find myself clicking the (invisible) page guide non-stop. Very irritating. I realize this is a feature many may like (though I'd personally prefer to do this in the ruler, rather than on the page), but can it be turned off when the page guides are invisible?

I assume that since so much time has passed since Matze's post that the answer is no.

The answer is still that currently one cannot lock the margins. We do view moveable invisible margins a bug, eg: invisible margins should never be draggable. So I expect that to be fixed sooner than lockable margins are added.